1. Field of the Invention
This invention relates generally to pyrotechnic compositions and, more specifically, to pyrotechnic compositions having combustion reaction products that include a high percentage of carbon dioxide at high temperatures. In particular, this invention relates to pyrotechnic compositions which include a fuel-component that is a compound having a relatively high carbon content and a relatively low hydrogen content. Examples of such compounds include, but are not limited to, aromatic polycarboxylic anhydrides, aliphatic polycarboxylic acid anhydrides, quinones, acetylenics, acid salts, polycyano compounds, substituted polynuclear compounds, polyanhydrides, polymeric anhydrides or polylactone compounds having combustion products having a relatively high long to short wavelength infrared output color ratio and/or a relatively high percentage of CO2 and a relatively low percentage of H2O.
2. Description of the Related Art
Infrared decoy flares are used by aircraft as protection against attack by heat seeking missiles. These flares are typically ejected from an aircraft and ignited to produce infrared (xe2x80x9cIRxe2x80x9d) radiation that simulates the infrared emissions of aircraft engines of the targeted aircraft. The IR emissions of the decoy flare are intended to confuse a heat seeking anti-aircraft missile, thereby causing the missile to turn away from the target aircraft toward the decoy flare.
Modern heat seeking anti-aircraft missiles typically employ seeker heads capable of distinguishing between short and long wavelength IR emissions. Long wavelength IR emissions are typically produced by aircraft components, such as hot jet engines. Short wavelength IR emissions are characteristic of gray-body materials having higher temperatures and/or heated water vapor. In this respect, missile seeker heads may be configured to compare particular IR output color ratios. As used herein, xe2x80x9ccolor ratioxe2x80x9d is defined as the ratio of long wavelength IR output (xe2x80x9cLWxe2x80x9d) to short wavelength IR output (xe2x80x9cSWxe2x80x9d).
Because seeker heads of anti-aircraft missiles are designed to identify IR characteristics of aircraft engine emissions, flare decoy burn requirements are dictated by the characteristics of aircraft engine IR emissions. Aircraft engines typically produce a spectrum of IR radiation characteristic of a gray-body radiator in the 600-900 degree Centigrade range. In this regard, a flare decoy should burn to produce IR emissions having a large percentage of long IR wavelengths, similar to aircraft engine emissions.
In the past, flares have been configured to include combustible flare pellets, which are ignited when a decoy flare is deployed. Flare pellets have typically included a shaped quantity of flare material coated with an ignition composition. For example, a typical flare pellet is made of a solid pyrotechnic composition that includes magnesium, xe2x80x9cTEFLONxe2x80x9d, and xe2x80x9cVITONxe2x80x9d (this composition is commonly known as xe2x80x9cMTVxe2x80x9d), the latter two components being commercially available from DuPont. Such conventional flare compositions suffer from several disadvantages. For example, they may emit IR radiation which does not correspond with IR emissions of the missile target, especially when used against missiles which measure or detect the IR color ratio of targets.
In order to address these and other problems, certain xe2x80x9ctwo colorxe2x80x9d decoy flare compositions have been developed which will generate IR color ratios more similar to that of targeted aircraft. For example, xe2x80x9ctwo colorxe2x80x9d boron-based and red phosphorous-based compositions that produce flare emissions with higher LW/SW color ratios than MTV have been developed. However, the IR output of such two color compositions typically degrades in a windstream, exhibiting increased short wavelength IR energy when a decoy flare is ejected from an aircraft. Generally, the output color ratio of such a flare changes with increases in wind speed until it no longer matches the signature of a jet engine exhaust at operating temperatures, thus allowing a heat seeking anti-aircraft missile to distinguish the decoy flare from the aircraft.
In order to address windstream IR emission degradation, several measures have been taken. For example, protective shields have been added to keep the wind stream from directly impinging on the flare plume. These devices tend to be cumbersome and relatively inefficient. In other cases, decoy flare devices which control mixing of air with the output of flare compositions have also been developed. These devices tend to be costly and/or mechanically complex.
In one respect this invention is a pyrotechnic composition having the property that combustion of the pyrotechnic composition produces a combustion product with a molecular ratio of CO2 to H2O of greater than about 1.0. In other embodiments this molecular ration may be greater than about 2.0 or 4.0, respectively. This composition may also have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 1.0 or, in another embodiment, greater than about 3.0. In one typical embodiment, the pyrotechnic composition includes a fuel component including at least one aromatic polycarboxylic acid anhydride. In this embodiment, the aromatic polycarboxylic acid anhydride may be, among other things, any one of benzene tetracarboxylic acid dianhydride, benzophenone tetracarboxylic dianhydride, benzene hexacarboxylic acid trianhydride, or a mixture thereof. In another embodiment, the pyrotechnic composition may include a fuel component including anthraquinone. In another embodiment, the pyrotechnic composition may have an oxidizing agent and an afterburning stoichiometry, in which the pyrotechnic composition includes an amount of oxidizing agent sufficient to supply between about 40% and about 95% of the stoichiometric amount of oxidizing agent required for complete combustion of the fuel component. In another embodiment, the pyrotechnic composition may have a fuel component, further include an oxidizing agent, and have an afterburning stoichiometry, in which the pyrotechnic composition includes between about 28% and about 40% by weight of the fuel component, and between about 45% and about 69% by weight of the oxidizing agent.
In another respect, this invention is a pyrotechnic composition having the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 3:1. In one embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 3:1 under windstream conditions of about Mach 0.2. In another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces a combustion product having a molecular ratio of CO2 to H2O of greater than about 1.0. In still another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 1:1 under windstream conditions of about Mach 0.2. In yet still another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 1:1 under windstream conditions of up to at least about Mach 0.75. In still yet another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than or equal to about 1.5:1 under windstream conditions of up to at least about Mach 0.7. In yet still another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than or equal to about 2:1 under windstream conditions of about Mach 0.2. In a further embodiment of this composition, the pyrotechnic composition may include a fuel component comprising at least one of an anhydride, polyactone, quinone, acetylenic compound, acid salt compound, polycyano compound, polynuclear compound, or a mixture thereof. In this regard, the fuel component may include at least one of an aromatic mono-anhydride, aromatic poly-anhydride, aliphatic mono-anhydride, aliphatic poly-anhydride, or a mixture thereof. The fuel component may include at least one of an aromatic polycarboxylic acid anhydride, an aliphatic polycarboxylic acid anhydride, or a mixture thereof. The fuel component may include at least one aromatic polycarboxylic acid anhydride. In another embodiment of this composition, the fuel component may include an aromatic polycarboxylic acid anhydride present in an amount of between about 12% and about 40% by weight. In still another embodiment, the fuel component may include an aromatic polycarboxylic anhydride having one or more nitro functionalities. In another embodiment of this compostion, the fuel component may include at least one of benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, benzene hexacarboxylic acid trianhydride, mellitic anhydride, or a mixture thereof. The fuel component may include at least one of benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, mellitic anhydride, or a mixture thereof. The fuel component may include benzene tetracarboxylic dianhydride. The fuel component may include benzophenone tetracarboxylic dianhydride. The fuel component may include benzene hexacarboxylic acid trianhydride. The fuel component may include an aliphatic polycarboxylic acid anhydride, the polycarboxylic acid anhydride being at least one of maleic anhydride, maleic anhydride derivative, succinic anhydride, or a mixture thereof. The fuel component may include a polycyano compound, the polycyano compound being at least one of an aromatic cyano compound, an aliphatic cyano compound, or a mixture thereof. The fuel component may include at least one quinone, the quinone being at least one of a p-quinone derivative, an aromatic polynuclear quinone derivative, or a mixture thereof. The fuel component may include at least one of a quinone bearing two or less nitro groups per molecule, a quinone bearing two or less oxime groups per molecule, an anthraquinone, or a mixture thereof. The fuel component may include anthraquinone. The fuel component may include at least one of a mono-nitroanthraquinone, a di-nitroanthraquinone, a p-quinone dioxime, or a mixture thereof. The fuel component may include at least one acid salt compound or a mixture of acid salt compounds. The fuel component may include at least one acetyleneic compound or a mixture of acetyleneic compounds. The fuel component may include at least one polynuclear compound or a mixture of polynuclear compounds. This pyrotechnic composition may further include a binding agent that includes at least one of an elastomeric polymer, an epoxy resin, or a mixture thereof. This pyrotechnic composition may further include an oxidizing agent, the oxidizing agent comprising at least one of an alkali metal nitrate, perchlorate, or a mixture thereof. Another embodiment of this composition may include a fuel component that may include at least one of a nitrilotriacetonitrile, a dicyanobenzene, a malononitrile dimer, a malononitrile derivative, cyanoguanidine, or a mixture thereof.
In another respect, this invention is a pyrotechnic composition including at least one of an aromatic mono-anhydride, aromatic poly-anhydride, aliphatic mono-anhydride, aliphatic poly-anhydride, or a mixture thereof.
In another respect, this invention is a pyrotechnic composition including at least one aromatic polycarboxylic anhydride fuel component. In one embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces a combustion product having a molecular ratio of CO2 to H2O of greater than about 2.0. In another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces a combustion product having a molecular ratio of CO2 to H2O of greater than about 4.0. In another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 1.0. In another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces a combustion product having a molecular ratio of CO2 to H2O of greater than about 4.0. In yet still another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 1:1. In yet still another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than about 1:1 under windstream conditions of up to at least about Mach 0.75. In yet still another embodiment of this composition, the pyrotechnic composition may have the property that combustion of the pyrotechnic composition produces infrared emissions having an output infrared color ratio of greater than or equal to about 2:1 under windstream conditions of about Mach 0.2. In yet still another embodiment of this compostion, the fuel component may include at least one of benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, benzene hexacarboxylic acid trianhydride, mellitic anhydride, or a mixture thereof The fuel component may include at least one of benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, mellitic anhydride, or a mixture thereof. The fuel component may include benzene tetracarboxylic dianhydride. The fuel component may include benzophenone tetracarboxylic dianhydride. The fuel component may include benzene hexacarboxylic acid trianhydride. The fuel component may include one or more nitro functionalities. In another embodiment of this composition, the polycarboxylic anhydride may be present in a concentration of between about 8% and about 60% by weight of the pyrotechnic composition. This composition may also further include an oxidizing agent. This composition may also further include a binding agent. The binding agent may include at least one curable reactive resin. The oxidizing agent may include at least one alkali metal nitrate, perchlorate, or a mixture thereof. The oxidizing agent may be present in a concentration of between about 40% and about 90% by weight of the pyrotechnic composition. The binding agent may include at least one of an elastomeric polymer, epoxy resin, or a mixture thereof. The binding agent may be present in a concentration of between about 1% and about 20% by weight of the pyrotechnic composition. In one embodiment of this composition, the fuel component may be benzene tetracarboxylic acid dianhydride and the binding agent may be reactive with the fuel component. In another embodiment, the reactive binding agent may include epoxy resin. This pyrotechnic composition may have a shape that is maintained by the binding agent, and may further include an ignition layer surrounding at least a portion of the pyrotechnic composition. Further, this pyrotechnic composition may be configured as a decoy flare pellet, or adapted to be used as a propellant in an air bag deployment system.
In another respect, this invention is a pyrotechnic pellet comprising a pyrotechnic composition that may include from about 8% to about 60% by weight of an aromatic polycarboxylic anhydride fuel component, from about 40% to about 90% by weight of an oxidizing agent, from about 1% to about 20% by weight of a binding agent; and an ignition layer surrounding at least a portion of the pellet. The fuel component may include at least one of benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, benzene hexacarboxylic acid trianhydride, mellitic anhydride, or a mixture thereof. The fuel component may include at least one of benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, mellitic anhydride, or a mixture thereof. The fuel component may include benzene tetracarboxylic dianhydride. The fuel component may include from about 15% to about 38% benzene tetracarboxylic dianhydride. The fuel component may include benzophenone tetracarboxylic dianhydride. The fuel component may include benzene hexacarboxylic acid trianhydride. In one embodiment of this, the binding agent may be a reactive binding agent. For example, the aromatic carboxylic anhydride may be benzene tetracarboxylic acid dianhydride and the reactive binding agent may be epoxy resin. In another embodiment, the binding agent may include an elastomeric polymer. In another embodiment, the oxidizing agent may include at least one of an alkali metal nitrate, perchlorate, or a mixture thereof. In another embodiment of this pellet, the pyrotechnic composition may further include at least one of an antioxidant, conductive material, burning rate catalyst, or a mixture thereof. In still another embodiment, the fuel component may include from between about 20% and about 35% by weight benzene tetracarboxylic acid dianhydride or mellitic anhydride, the binding agent may include from about 2% to about 8% by weight synthetic rubber, and the oxidizing layer may include from about 60% to about 80% by weight potassium perchlorate. In yet still another embodiment, a pyrotechnic composition may have an afterburning stoichiometry, including an amount of oxidizing agent sufficient to supply between about 40% and about 95% of the stoichiometric amount of oxidizing agent required for complete combustion of the fuel component. In yet another embodiment, a pyrotechnic composition may have an afterburning stoichiometry, and include between about 28% and about 40% by weight of the fuel component, and between about 45% and about 69% by weight of the oxidizing agent. In still yet another embodiment, the pellet may be adapted to be received and combusted in a flare having a flare housing having one or more openings extending from an interior of the flare housing to an exterior of the flare housing, and in which the openings may be configured to allow partially oxidized combustion materials generated by partial oxidation of the fuel component within the flare housing to escape from the flare interior and to be further oxidized outside the flare housing. In still yet another embodiment, a pellet may be adapted to be received and combusted in an interior of a first flare housing of a flare, wherein the first flare housing may be coupled to a second flare housing having one or more outlet openings, wherein the first flare housing may have one or more openings extending from the interior of the first flare housing to an interior of the second flare housing and configured to allow partially oxidized combustion materials generated by oxidation of the fuel component within the first flare housing to escape from the first flare housing interior into the second flare housing interior, wherein the partially oxidized materials may be oxidized further within the second flare housing interior so that additional combustion materials are generated within the second flare housing, and wherein the second flare housing may have one or more outlet openings extending from the interior of the second flare housing to allow the original combustion materials and said additional combustion materials to escape and create a propellant force to propel the flare. The second flare housing may have one or more inlet openings adapted to allow oxygen containing gas into the interior of the second flare housing. In another embodiment, a pellet may be adapted to be received and combusted in a system for deploying air bags, the deployment system configured to allow combustion of materials generated by oxidation of the fuel component to inflate the airbag.
In yet another respect, this invention is a pyrotechnic composition for use in a system to deploy air bags, in which the pyrotechnic composition may have a fuel component with a molecular ratio of CO2 to H2O of greater than about 1.0, and may have a flame temperature of less than or equal to about 1800xc2x0 C. In one embodiment of this composition, the fuel component may include at least one of a mixed lactone polymer of hydroxyacetic acid, a mixed lactone polymer of lactic acid, a mixed lactone polymer of tartaric acid, maleic anhydride, phthalic anhydride, dicyandiamide, or a mixture thereof. In another embodiment, the pyrotechnic composition may further include a burning rate catalyst. In yet another embodiment, the pyrotechnic composition may include a fuel component including at least one aromatic polycarboxylic acid anhydride. The aromatic polycarboxylic anhydride may be any one of benzene tetracarboxylic acid dianhydride, benzophenone tetracarboxylic dianhydride, benzene hexacarboxylic acid trianhydride, or a mixture thereof. In another embodiment, the pyrotechnic composition may include a fuel component including anthraquinone.
In another respect, this invention is a decoy flare including a first flare housing having an interior and exterior and a pyrotechnic composition adapted to be received in the interior of the flare housing. The pyrotechnic composition may include from about 8% to about 60% by weight of an aromatic polycarboxylic anhydride fuel component, from about 40% to about 90% by weight of an oxidizing agent, from about 1% to about 20% by weight of a binding agent, and an ignition layer surrounding at least a portion of the pyrotechnic composition. The pyrotechnic composition may be formed in the shape of a pellet and adapted to be ejected from the first flare housing and simultaneously ignited. The pyrotechnic composition may also have an afterburning stoichiometry in which it may include an amount of oxidizing agent sufficient to supply between about 40% and about 95% of the stoichiometric amount of oxidizing agent required for complete combustion of the fuel component. In this regard, the pyrotechnic composition may include from about 28% to about 40% by weight of the fuel component and from about 45% to about 69% by weight of the oxidizing agent, and the first flare housing may have one or more openings extending from an interior of the first flare housing to an exterior of the first flare housing. These openings may be configured to allow partially oxidized combustion materials generated by partial oxidation of the fuel component within the flare housing to escape from the first flare housing interior and to be further oxidized outside the first flare housing. In another embodiment, the flare may further include a second flare housing having an interior and an exterior, and the first housing may be coupled to the second housing. In this embodiment, the pyrotechnic composition may have an afterburning stoichiometry and may include an amount of oxidizing agent sufficient to supply between about 40% and about 95% of the stoichiometric amount of oxidizing agent required for complete combustion of the fuel component. In this regard, the pyrotechnic composition may include from about 28% to about 40% by weight of the fuel component and from about 45% to about 69% by weight of the oxidizing agent, and the pyrotechnic composition may be adapted to be received and combusted in the interior of the first flare housing. Further, the first flare housing may have one or more outlet openings extending from the interior of the first flare housing to the interior of the second flare housing, and these openings may be configured to allow partially oxidized combustion materials generated by oxidation of the fuel component within the first flare housing to escape from the first flare housing interior into the second flare housing interior where the partially oxidized materials may be oxidized further within the second flare housing interior so that additional combustion materials are generated within the second flare housing. The second flare housing may have one or more outlet openings extending from the interior to the exterior of the second flare housing to allow the additional combustion materials to escape from the interior of the second flare housing so that a propellant force may be generated to propel the flare. In another embodiment, the second flare housing may have one or more inlet openings adapted to allow oxygen containing gas into the interior of the second flare housing. In another embodiment, the first flare housing may have one or more openings extending from an interior of the first flare housing to an exterior of the first flare housing, the openings configured to allow combustion materials generated by oxidation of the fuel component within the flare housing to escape from the flare interior so that a propellant force may be generated to propel the flare. In yet still another embodiment of this flare, combustion of the fuel component may produce a long to short infrared color ratio of greater than about 1.0. The flare housing may be adapted for use in an aircraft decoy flare deployment system. Combustion of the pyrotechnic composition may produce infrared emissions having an output infrared color ratio capable of decoying a missile having a seeker head configured to detect and distinguish color ratio of infrared emissions. In one embodiment, the decoy flare may include a pyrotechnic composition including an aromatic polycarboxylic anhydride that may be any one of benzene tetracarboxylic acid dianhydride, benzophenone tetracarboxylic dianhydride, benzene hexacarboxylic acid trianhydride, or a mixture thereof.